Page 1 of 3 123 LastLast
Results 1 to 15 of 42

Thread: Help for JBL k2

  1. #1
    Member
    Join Date
    May 2021
    Location
    Italia
    Posts
    57

    Help for JBL k2

    Good morning, I ask you for help to restore to the best of JBL K2, unfortunately they have decentralized 435BE drivers and in my opinion they are useless, even the diaphragms are badly put only one diaphragm is recoverable, the other is gone. I am thinking of replacing Driver and Diaphragm with a new pair but being the 435Be not found I have to settle for mounting either 435Al-1 or alternatively 2435HPL. I ask if replacement is possible, do they mount on the horn?

  2. #2
    Administrator Mr. Widget's Avatar
    Join Date
    Apr 2003
    Location
    San Francisco
    Posts
    10,991
    Welcome to the forum, I saw your other thread and it sounds like you have a nice JBL collection.

    Unfortunately the JBL of today is pretty poor at supporting their products. You used to be able to buy repair parts to support 50 year old JBLs, today it can be difficult to even get them repaired under warranty. I am not sure if there are any current JBLs that use the 435Be. I donít think they are still producing that driver and I donít think they ever supplied replacement diaphragms for them.

    Obviously swapping out both 435Be drivers would be your best course of action, but if that is not possible and you can get the 435AL drivers they will bolt right in and will sound close to the same. A network modification will be required.

    Anecdotally, there have been 2435s with widely varying performance. This is likely due to someone dumping factory rejects or partially blown drivers from PA systems. Personally I would avoid those drivers unless you had proof that they were new ďAĒ stock drivers.


    Widget

  3. #3
    Member
    Join Date
    May 2021
    Location
    Italia
    Posts
    57
    Thanks for the reply, I would buy the new drivers I had thought of both the 435AL-1 (acquaplas), and the 2435hpl which have the beryllium diaphragm, also I could use my rear cover of the 435Be to transform the 2435hpl to something very close to the 435Be.
    What do you think about it?

  4. #4
    Administrator Mr. Widget's Avatar
    Join Date
    Apr 2003
    Location
    San Francisco
    Posts
    10,991
    I think that back cap will fit the 2435, but I personally would not open these drivers. As I recall, the back cap holds the diaphragm in place. If the diaphragm moves slightly the performance will be affected. Also as I stated, based on numerous posts by members on this forum, quite a few 2435 drivers that were sourced through various means were not satisfactory.

    I do not think the beautifully made 435AL/435Be back caps provide a performance upgrade over the smaller back cap of the Pro series of 3" drivers. I think it is an aesthetic change... though there has been some debate on that.

    Do you have factory built K2-S9800s? If yes, have you tried to have these repaired through contacting Harman in Europe?


    Widget

  5. #5
    Member
    Join Date
    May 2021
    Location
    Italia
    Posts
    57
    I bought the k2s knowing of a defect in the 435be drivers and paying for them relatively little. I thought it was the diaphragm instead inside the driver was decentralized, it should be unglued and centered well however the beryllium / aquaplas membranes are nowhere to be found as spare parts.
    I think I can easily live with a new 435AL - 1 driver at this point if you think it will snap into my h9800 horn.

  6. #6
    Administrator Mr. Widget's Avatar
    Join Date
    Apr 2003
    Location
    San Francisco
    Posts
    10,991
    Physically the two drivers are identical so yes, you can easily bolt them in, but you must replace both so that they match.

    Have you tried to contact Harman to see if they would sell you the correct drivers? It might be expensive but it will make your speakers worth an order of magnitude more than without them. Furthermore if they are available today itís very likely they will not be available soon.


    Widget

  7. #7
    Senior Member
    Join Date
    Apr 2003
    Location
    GTA, Ont.
    Posts
    4,945
    RobH3606 fixed one of his eBay bought 2431H drivers where the internal pole piece had broken loose from the magnet after he dropped it.

    This sounds like what might have happened to the OP's 435Be.

    The diaphragm's voice-coil is plastic protected and wrapped ( in teflon tape ?? ) ( meaning, even though the OP's diaphragm might appear to be bad <> it might just be "captured tight within the gap" & needing an extra careful release ( to be saved ) .

    See Rob's How to Ruin Your Day thread to review his Best Save of the Decade.

    A preview :







  8. #8
    Member
    Join Date
    May 2021
    Location
    Italia
    Posts
    57
    He was good, very good.
    I think for now I will take two 435Al-1 I am quite convinced that it will sound very good too, at the limit through the resistive network already present in the crossover I will change the attenuation .... I expect that the aluminum is less lively than the beryllium .... for the rest I think the engine is the same.
    I have already asked Harman for no spare parts unfortunately.
    For the rest the speakers are very nice, in my opinion it is a more than acceptable solution

  9. #9
    Member
    Join Date
    May 2021
    Location
    Italia
    Posts
    57
    He was good, very good.
    I think for now I will take two 435Al-1 I am quite convinced that it will sound very good too, at the limit through the resistive network already present in the crossover I will change the attenuation .... I expect that the aluminum is less lively than the beryllium .... for the rest I think the engine is the same.
    I have already asked Harman for non spare parts unfortunately.
    For the rest the speakers are very nice, in my opinion it is a more than acceptable solution

  10. #10
    Member
    Join Date
    May 2021
    Location
    Italia
    Posts
    57
    unfortunately the 435AL-1 is not available as a spare .....
    At this point I have to take either a pair of 2430s or a pair of 2431s.
    Which one do you recommend to insert in place of the 435AL-1 and that it attaches to my horn 9800?

  11. #11
    Senior Member pos's Avatar
    Join Date
    May 2007
    Location
    Paris, France
    Posts
    2,632
    Swapping drivers will require a modification of the crossover, or going active.
    If you are prepared for such an endeavor (measurements + simulations, etc.) then going for a 4" driver might be the best solution.
    Something like a 476Mg would be ideal, if you manage to get a pair.

  12. #12
    Administrator Mr. Widget's Avatar
    Join Date
    Apr 2003
    Location
    San Francisco
    Posts
    10,991
    Quote Originally Posted by pos View Post
    Swapping drivers will require a modification of the crossover, or going active.
    True if you want to achieve the best possible performance, but I believe Paul001 is willing to do a direct driver swap and live with the performance hit.

    Quote Originally Posted by pos View Post
    If you are prepared for such an endeavor (measurements + simulations, etc.) then going for a 4" driver might be the best solution.
    Something like a 476Mg would be ideal, if you manage to get a pair.
    Agreed, and properly implemented the 476Mg would be a definite upgrade, however I don't think even JBL can get them anymore. They have resorted to using rebadged Radian drivers.


    Widget

  13. #13
    Member
    Join Date
    May 2021
    Location
    Italia
    Posts
    57
    I don't think the diaphragm change between 435AL 1 and 435 Be has a heavy influence on listening, obviously the filter is better regulated on the beryllium... let's see what happens the k2 also have a medium adjustment to intervene on. In the meantime I am also intervening on the 435Be drivers that I have disassembled, cleaned and built a dima to re-enter them, currently I am in the process of bonding with specific two-component epoxy glue.

  14. #14
    Member
    Join Date
    May 2021
    Location
    Italia
    Posts
    57
    Some photos of the work done, once the upper crown has been detached by screwing the screws must be carried out a thorough cleaning of everything, at this point a robust dima must be built to reinsert the upper crown precisely, everything must be reglued with two epoxy components suitable for magnetic metals, I used a specific pattex, the 435 BE drivers now work perfectly, I tried with frequency generator and even at 700hz- 800hz they are good in working without emitting any particular noise, also I am buying a pair of 435AL to store.




    Name:  7.jpg
Views: 320
Size:  57.3 KB

    [ATTACH]8904Name:  1.jpg
Views: 333
Size:  164.4 KBName:  3.jpg
Views: 343
Size:  210.3 KBName:  2.jpg
Views: 327
Size:  122.1 KB
    Attached Images Attached Images  

  15. #15
    Member
    Join Date
    May 2021
    Location
    Italia
    Posts
    57
    Il driver che soffriva di creep surround aveva questo aspetto al momento dello smontaggio,
    decentralization prevents the coil from flowing freely inside magnetic cavities, and in working it makes friction in the neodymium.

    Name:  5.jpg
Views: 324
Size:  165.2 KBName:  6.jpg
Views: 343
Size:  150.7 KBName:  6.jpg
Views: 343
Size:  150.7 KB

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •